An air-bag device is a device to protect automobile occupants in the case of a collision of the automobile by inflating the air-bag instantly. The air-bag device usually includes: an inflator serving as a gas generator; and an air-bag made of a synthetic fabric designed to inflate with an inflator gas. The gas ejected from the inflator is very hot. Therefore, the periphery of an inflator connection opening, with which the hot gas makes direct contact, is treated to increase its heat resistance.
For example, there has been proposed a base fabric for an air-bag in the form of a bag, whose inlet for an inflator gas has increased heat resistance because a part of the air-bag for connection with the inflator is partially coated with a thick resin (Patent Document 1). However, this technique is to apply a light coating of resin to the entire surface of the base fabric and thereafter apply the second coating to a necessary part, and thus has a problem in that the coating has to be performed a plurality of times and this leads to increased costs.
On the other hand, there has been proposed an air-bag in which, for the purpose of increasing the heat resistance of its inner periphery of an inflator connection opening, a base fabric for an air-bag main body and a flame-resistant fabric are arranged and a layer of a heat insulating resin resistant to temperatures up to at least 250° C. is provided between the base fabric and the flame-resistant fabric (Patent Document 2). However, the inflator gas currently used is becoming hotter and hotter, and the temperature at the moment of explosion may be 2000° C. or higher. Therefore, usual heat-resistant resins cannot withstand such a hot gas.
Furthermore, there has been proposed a method by which a reinforcing fabric or the like is polymerized on the periphery of an opening for connection with an inflator and the fabric is sewed on the periphery (Patent Document 3). This technique is to stack two reinforcing fabrics on the base fabric for an air-bag main body. However, the structure of the reinforcing fabric itself is not disclosed, and it is unknown whether the reinforcing fabric itself can withstand the high temperatures of the inflator gas currently used.